(a) Field of the Invention
The present invention relates to a paging method in a broadband wireless communication system.
(b) Description of the Related Art
A femtocell base station represents a very small base station that is installed to provide services to users within a 30-meter radius such as in houses or buildings. The femtocell base station is installed in a macrocell, and it provides services by having excellent QoS that is better than the case of providing the service to the user through a macrocell base station.
Also, since the femtocell base station is connected to the network by using a general-purpose Internet circuit, the service can be provided with inexpensive installation and maintenance costs. The service is provided to the user in any area in which the Internet is connected.
A terminal is switched to be in an idle mode when a service provided through the macrocell base station is finished. In the idle mode, the terminal receives a paging signal and updates a position to receive a paging service such as a call receiving service from the network or the base station. In the idle mode entering process, the macrocell base station provides a paging group ID, a temporary identifier for identifying terminals in a paging group, and paging information (e.g., paging period and paging offset) provided by a paging controller to the terminal.
The paging group ID is allocated to a paging group configured with at least one base station. The paging controller transmits the same paging message to all the base stations belonging to the paging group ID. The base stations in the paging group broadcast the received paging message according to a paging period. When moving to a base station belonging to another paging group ID, the terminal updates the paging group ID, the temporary identifier, and the paging information through a position update process.
Currently, the femtocell base station provides the same paging service as the macrocell base station, which will now be described with reference to FIG. 1 and FIG. 2. FIG. 1 shows a general case when different paging group ID's are allocated to a macrocell base station and a femtocell base station, and FIG. 2 shows a general case when the same paging group ID's are allocated to a macrocell base station and a femtocell base station.
As shown in FIG. 1, when the terminal moves from the femtocell base station 20-1 to 20-4 to the macrocell base station 10 or from the macrocell base station 10 to the femtocell base station 20-1 to 20-4, it is required to update the position of the terminal. When the terminal moves frequently, signaling overhead caused by the position update process is increased. This is because the terminal can receive the service from the base station only by acquiring a paging group ID through a terminal position update process since the paging group ID used by the macrocell base station 10 is different from the paging group ID used by the femtocell base stations 20-1 to 20-4.
Therefore, as shown in FIG. 2, when the paging group ID used by the femtocell base stations 20′-1 to 20′-4 are the same as the paging group ID used by the macrocell base station 10′, the signaling overhead can be reduced when the terminal has no need to perform the position update process caused by movement between the femtocell base stations 20′-1 to 20′-4 and the macrocell base station 10′. On the contrary, when the femtocell base stations 20′-1 to 20′-4 and the macrocell base station 10′ use the same paging group ID, the same paging message is transmitted from the macrocell base station 10′ and the femtocell base stations 20′-1 to 20′-4 to the terminal to thereby increase signal interference.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.